Steve from B.C. has problems with Toung & Groove pine boards on the ceiling of a log home, where the boards were cut very roughly where ceiling sections came together. Steve was looking for some kind of discrete trim that would cover the ends of the boards.
I suggested thin pine boards, taken from wainscotting only 5/16 inch thick, cutting off the toung and groove, beveling the joint and creating a little bevel on the outside corner. This will give a non-obtrusive cover for the corner.
Remember that the real reason for being of almost all molding is to hide cracks of some sort.